Re: Accuracy of instruments
Re: Accuracy of instruments
- Subject: Re: Accuracy of instruments
- From: Terry Wyse <email@hidden>
- Date: Fri, 2 Nov 2007 13:33:21 -0400
On Nov 2, 2007, at 2:09 AM, Mike Strickler wrote:
It is not simply the case that more and more accuracy/consistency is
always useful. When the final measure of color is the human visual
system, which has extremely poor repeatability AND interinstrument
agreement (should we also talk about viewing conditions and THEIR
consistency?), there are limits to the usefulness of accuracy of
your spectrophotometers for this application.
Agreed, but the human vision system is VERY good at making comparison
"measurements". It can easily detect differences of sub-1 deltaE in
neutrals. I've done comparisons myself where I built profiles using a
highly-accurate proofing system (GMG) and verified that the match was
< .5 dE but measured with 2 different spectros (DTP70 and iSis, both
very repeatable instruments). Visually, there was a difference between
the proofs that was easily discernible. The point is, you can have a
dE match up the wazoo but because of the differences in the spectros,
the human eye can definitely tell there's a difference. So I guess
what I'm saying is that I don't by the argument that today's spectros
have an accuracy below the threshold of what the average human can see.
And by the way, I DO have special ".25 dE glasses" that really help
when evaluating color differences. They also come with a big nose and
mustache attached. Quite special I think. I put them on when I really
what to intimidate a pressman or supposed "color expert". When they
see my special glasses, they immediately back away from the viewing
booth and will sometimes even kneel in front of me. I must say, I get
a kick out of it.
:-)
Regards,
Terry Wyse
_____________________________
WyseConsul
Color Management Consulting
G7 Certified Expert
email@hidden
704.843.0858
http://www.wyseconsul.com
http://www.colormanagementgroup.com
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